If you don't have an agreement with the owner of the pics, then they're not yours to use. Take them down and move on.
Not necessarily. He says the other company has been involved in how the pictures have been used. There have been debates on how the images should be displayed, strategies on the use of the pictures have been discussed. A court on reviewing the evidence might very well find that some sort of license agreement exists for the use of the pictures.
My advice would be to ask a lawyer specialised in copyright law.